1. Field of the Invention
This invention relates, in general, to means for, and process of, registering relatively small, flat objects each having a defined opening whereby the objects can each be registered or centered for further handling. In particular, the invention relates to registration means having utility in combination with apparatus for the decorative printing of such objects. Even more particularly, the invention is concerned with registration means having utility in silk-screen and offset printing machines for application of decorative or informational matter to discs having a centrally disposed opening such as compact discs.
2. Description of the Prior Art
The registration of various work pieces prior to the performance of work thereon is commonly done. Thus, for example, in the decorative silk-screen printing of various substrates such as flats and plastic bottles these members must first be registered or oriented relative to the printing head so that the printing ink is applied to the substrate at the desired location. Otherwise, as will be readily appreciated, the informational or aesthetic value of such printing may be lessened and, in some cases, even necessitate discarding the object to waste. This, of course, is highly undesirable as such wastage results in increased costs of operation. The potential for such a problem happening is particularly great where more than one color of ink is to be applied to the substrate surface.
One method for the screen printing of compact discs involves, in general, the transporting of the discs on a rotatable annular-shaped member in a spaced-apart fashion in a horizontally disposed circular-defined path. The compact discs are each transported, in turn, to a plurality of printing locations whereat such are silk-screen printed at each location with a pattern of ink of desired color. The ink pattern is cured or dried in conventional manner, e.g., by ultra-violet curing means, between each application.
In order to ensure that a compact disc is properly located or registered on the transport member and in proper relationship to the printing head for the screen printing operation, each disc is registered on the transport member. This is accomplished before a disc is silk-screen printed with the first color of the pattern to be applied. The precise registration of a compact disc for screen printing is extremely important, as such printing may cover substantially the entire surface of one side of a disc and, moreover, may involve the application of as many as six (6) different colors of ink. Such a decoration may include not just textual material but pictorial illustrations as well.
One compact disc printing system known heretofore to those in the screen printing art involves the registration of each compact disc following loading of the disc onto the transport member or device. Thus, in this system, a registration means comprising a registration pin located vertically above the transport member causes the registration or centering pin, in general, to be lowered whereby the free end thereof can intrude into the center opening of the compact disc from the top side or surface thereof. This pin intrusion causes the compact disc to move somewhat, even though a relatively small distance, to become centered or registered, as desired. Thus, the bottom side or surface of the compact disc, as loaded onto the transport member, moves across and in contact with the surface of the disc fixture in which the compact disc is located on the transport member. This movement, though small, is somewhat undesirable, however, as the surface of the compact disc in contact with the disc fixture, in this case the bottom surface, is the surface through which the recorded music or other information on the disc is read in a disc player. The result of such movement is occasional marring or scratching of the read-through surface. At the least, the disc may be cosmetically damaged. More importantly, however, there may also be damage to the fidelity of the disc. In such a case, the compact disc is necessarily discarded to waste. Registration by the centering pin piercing the centerhole from above can also damage the centering hole of the disc, again affecting its overall quality. This can occur even without damage to the disc cosmetically, or to its fidelity.
Another, somewhat more suitable and improved means of registering a compact disc prior to its being silk screen printed is disclosed in U.S. Pat. No. 5,165,340, which issued to William M. Karlyn et al on Nov. 24, 1992. The registration or registering means for a compact disc, as disclosed in that patent, is provided, quite advantageously, on the underneath side of the transport member. A registering means, moreover, is provided in opposition to each disc fixture located on the transport member. With such an arrangement, the compact disc is registered, i.e., centered, as it is being located in the disc fixture, not afterwards. Thus, as a compact disc is being placed into the disc fixture, the elongated registration pin of the registration means is caused to be raised vertically upwardly so as to intrude into the disc centerhole. The registration pin being located at the centerpoint of the fixture, the compact disc is, accordingly, centered in the desired location in the fixture whereby the surface to be printed is precisely registered or oriented to receive subsequent applications of printing ink. After the compact disc is registered, in fact almost simultaneously, the elongated registration pin is caused to be withdrawn from the disc's centerhole and vacuum is applied to the bottom surface of the disc. Thus, the compact disc is held and maintained in its registered location and orientation until after having been subjected to work, e.g. multiple printing applications. Then, the vacuum is released so that the printed compact disc can be off-loaded from the transport member.
Although quite satisfactory results have been obtained in the silk-screen printing of compact discs with the registration means disclosed in U.S. Pat. No. 5,165,340, the use thereof is attendant with certain disadvantages. As a registration means is provided for each disc fixture, this increases the overall cost of a screen printing machine. Perhaps, more importantly, however, it also provides for a greater number of possibilities where misregistration of a compact disc on the transport member might occur. These possibilities occur, primarily, due to tolerance variations during manufacture of the multiple number of registration means and the assembly of such a registration means in combination with each disc fixture and the transport member.